Egg squat and laying...how long in-between?

How soon do most birds start laying after their initial squat?
My 17 wk. RIR just squatted this weekend, I didn't expect it this soon.
What are the average time periods between onset of squatting and laying their first egg?
I understand they probably vary a great deal.
My banty squatted one day, and laid the next.

I think mine were between a week and a half and two weeks. One of my Marans pullets started squatting last week and hasn't laid yet. My bet is that is varies though, chickens don't seem to like following set rules

Two of my girls have been squatting for about a week. The other five have not. My Easter egger, a non squatter, laid her first egg today. I was shocked since I thought one of the two squatters would surely be first to lay. Not the case. Got a beautiful green egg!!!